1. Field of the Invention
The present invention relates to detecting a type of a disc, and, more particularly, to a method of and apparatus for detecting whether a cartridge-type disc is loaded in a disc drive by using a closing time of a disc tray of the disc drive.
2. Description of the Related Art
A cartridge-type disc, constructed with a disc and a cartridge surrounding the disc, has been developed to protect the disc from scratches or dust particles. FIG. 1A shows an appearance of the cartridge-type disc. The cartridge-type disc includes sensor holes H1, H2, and H3 for distinguishing the cartridge-type disc from a general-type disc when loaded in a disc drive and for indicating various conditions of the cartridge-type disc. FIG. 1B shows a schematic structure of the disc drive. The disc drive comprises a disc tray (not shown) for holding a disc, a spindle motor 100 for moving the disc tray, detection switches SW1, SW2, SW3, and SW4 for obtaining information about various conditions of the cartridge-type disc.
When the cartridge-type disc of FIG. 1A is inserted into the disc drive of FIG. 1B, the sensor holes H1, H2, and H3 come in contact with the detection switches SW1, SW2, and SW3, respectively, in the disc drive. The sensor holes indicate various states of the disc, such as whether the cartridge-type disc is writable, whether the cartridge-type disc is single-sided or double-sided, or whether the cartridge is unsealed such that the disc has been removed. In the disc drive of FIG. 1B, information about the state of a cartridge-type disc can be obtained via the detection of switches SW1, SW2 and SW3 being selectively in contact with the sensor holes H1, H2, and H3, respectively.
An additional detection switch SW4, for distinguishing whether the cartridge-type disc is loaded in the disc drive, is also included in the disc drive. When it is detected via the switch SW4 that the cartridge-type disc is loaded in the disc drive, information on the loading condition is transferred to a controller (not shown) in the disc drive. Then, the controller receives the information from the other switches (i.e., SW1, SW2, and SW3) to detect the state of the cartridge-type disc. The state of the cartridge-type disc is interpreted by the controller according to signals corresponding to the ON-state or OFF-state of the switches SW1, SW2, SW3, and SW4.
Accordingly, if the detection switch SW4 malfunctions, operations for obtaining information about the state of the cartridge-type disc via the switches SW1, SW2, and SW3 may not be performed. In practice, mechanical wear due to frequent pressure applied on the switch SW4 whenever the cartridge-type disc of FIG. 1B is inserted into or removed from the disc tray may cause the disc drive to malfunctions. For example, the switch SW4 may not be released from a pressed state, or vice versa. Since the disc detection is performed when the cartridge-type disc is loaded in the disc tray, the fault of the switch will inevitably occur in time. When this happens, a user has to perform a difficult and time-consuming operation to replace the switch with a new one.